1. Field of the Invention
This invention relates to an improved rotor and shaft assembly for permanent magnet, brushless motors, and more particularly, to a high performance assembly that is inexpensive to manufacture.
The rotor in a permanent brushless motor is a critical component. The magnets are mounted on the rotor and the torque is transmitted to the motor output shaft via the rotor. A rotor-shaft assembly without slip is critical to proper operation in a servo motor application because the servo motor operates bi-directionally at full torque.
2. Description of the Prior Art
There are several prior art ways to secure the rotor to the shaft. Usually, in the prior art, the rotor is machined from solid steel stock. A key and key way can be used to lock the rotor to the shaft and prevent mechanical movement of the rotor relative to the shaft. The problem with this approach is that some clearance is required to slip fit the two parts together. Therefore, you have a built-in rotational play (i.e. slip) when the motor changes direction. Adhesive can be used to prevent slippage, but repairs arc difficult to such assemblies and applying the adhesive requires additional labor. A thermal shrink fit can be used to secure the rotor to the shaft, but again this process requires labor, equipment, and it slows the manufacturing process.